Hi Chris, for the sub-d plugins that's the correct place. With those in place there will be new commands with those same filenames available to use on a shortcut key. For example with the plugin files _ImportObj.js and _ImportOBJ.htm you should now be able to put _ImportObj as the command part of a shortcut key to trigger that plugin.

For CustomUI, make sure you've got the version for v4 (link near the top of http://moi3d.com/forum/index.php?webtag=MOI&msg=6507.1) and then there are some detailed instructions in the links above. For v4 the files go into the appdata folder which is at ~/Library/Application Support/Moi .

Note that Apple hides the ~/Library folder by default, to show it see the section "How to view a Mac's ~/Library folder" here:
https://www.macworld.co.uk/how-to/mac-software/show-hidden-files-mac-3520878/

@Stefano, for lighting options it depends on a section of your moi.ini file to have been populated with lighting settings from a separate older plug-in. To make it work, install the Lighting Options plugin from here and run it: http://moi3d.com/forum/index.php?webtag=MOI&msg=5222.43 that should then fill in the section of moi.ini that the CustomUI lighting menu is looking for.

- Michael